Inorganic Oxide Surfaces Research Articles

Hydrophobization of Inorganic Oxide Surfaces via Ring-Opening Polymerization of Cyclic Siloxane Vapor.

The ability to control the surface chemistry of inorganic oxides has a profound impact on numerous applications, including lubrication, antifouling, and anticorrosion. While often overlooked as potential modifying agents given their lack of traditional functional groups, siloxanes have recently been shown to react readily with and covalently attach to inorganic oxide surfaces. Herein, we examine the reactions of cyclic siloxane vapor with solid interfaces via a ring-opening polymerization (ROP) initiated by the inherent acid/base characteristics of several smooth inorganic oxide surfaces. Surfaces are characterized by ellipsometry, dynamic contact angle analysis, and X-ray photoelectron spectroscopy (XPS). This technique requires no additional solvents and very little reactant to produce nanometer-thick hydrophobic surfaces that exhibit low contact angle hysteresis. Additional studies with particulate surfaces suggest that this method prepares conformal coatings regardless of surface architecture.

Forced Gradient Copolymer for Rational Design of Mussel-Inspired Adhesives and Dispersants.

In recent years, there has been considerable research into functional materials inspired by living things. Much attention has been paid to the development of adhesive materials that mimic the adhesive proteins secreted by a mussel's foot. These mussel-inspired materials have superior adhesiveness to various adherents owing to the non-covalent interactions of their polyphenolic moieties, e.g., hydrogen bonding, electrostatic interactions, and even hydrophobic interactions. Various factors significantly affect the adhesiveness of mussel-inspired polymers, such as the molecular weight, cross-linking density, and composition ratio of the components, as well as the chemical structure of the polyphenolic adhesive moieties, such as l-3,4-dihydroxyphenylalanine (l-Dopa). However, the contributions of the position and distribution of the adhesive moiety in mussel-inspired polymers are often underestimated. In the present study, we prepared a series of mussel-inspired alkyl methacrylate copolymers by controlling the position and distribution of the adhesive moiety, which are known as "forced gradient copolymers". We used a newly designed gallic-acid-bearing methacrylate (GMA) as the polyphenolic adhesive moiety and copolymerized it with 2-ethylhexyl methacrylate (EHMA). The resulting forced gradient adhesive copolymer of GMA and EHMA (poly(GMA-co-EHMA), Poly1) was subjected to adhesion and dispersion tests with an aluminum substrate and a BaTiO3 nanoparticle in organic solvents, respectively. In particular, this study aims to clarify how the monomer position and distribution of the adhesive moiety in the mussel-inspired polymer affect its adhesion and dispersion behavior on a flat metal oxide surface and spherical inorganic oxide surfaces of several tens of nanometers in diameter, respectively. Here, forced gradient copolymer Poly1 consisted of a homopolymer moiety of EHMA (Poly3) and a random copolymer moiety of EHMA and GMA (Poly4). The composition ratio of GMA and the molecular weight were kept constant among the Poly1 series. Simultaneous control of the molecular lengths of Poly3 and Poly4 allowed us to discuss the effects on the distribution of GMA in Poly1. Poly1 exhibited apparent distribution dependency with regard to the adhesiveness and the dispersibility of BaTiO3. Poly1 showed the highest adhesion strength when the composition ratio of GMA was approximately 9 mol% in the portion of the Poly4 segment. In contrast, the block copolymer consisting of the Poly3 segment and Poly4 segment with only adhesive moiety 1 showed the lowest viscosity for dispersion of BaTiO3 nanoparticles. These results indicate that copolymers with mussel-inspired adhesive motifs require the proper design of the monomer position and distribution in Poly1 according to the shape and characteristics of the adherend to maximize their functionality. This research will facilitate the rational design of bio-inspired adhesive materials derived from plants that outperform natural materials, and it will eventually contribute to a sustainable circular economy.

Enantioselective Michael addition of aldehydes to maleimides catalysed by surface-adsorbed natural amino acids

Chiral hybrid materials obtained by adsorption of primary α-amino acids on the surface of inorganic oxides are economic, recyclable, highly enantioselective heterogeneous catalysts for the Michael addition of aldehydes toN-substituted maleimides.

Insights on Alanine and Arginine Binding to Silica with Atomic Resolution.

Interactions of biomolecules with inorganic oxide surfaces such as silica in aqueous solutions are of profound interest in various research fields, including chemistry, biotechnology, and medicine. While there is a general understanding of the dominating electrostatic interactions, the binding mechanism is still not fully understood. Here, chromatographic zonal elution and flow microcalorimetry experiments were combined with molecular dynamic simulations to describe the interaction of different capped amino acids with the silica surface. We demonstrate that ion pairing is the dominant electrostatic interaction. Surprisingly, the interaction strength is more dependent on the repulsive carboxy group than on the attracting amino group. These findings are essential for conducting experimental and simulative studies on amino acids when transferring the results to biomolecule-surface interactions.

Unraveling how nanoscale curvature drives formation of lysozyme protein monolayers on inorganic oxide surfaces

The development of nanostructured material interfaces is critical to various application areas spanning diverse fields such as medicine, energy, and sensing. One of the most promising areas involves nanomedicine and drug delivery and involves the formation of noncovalently adsorbed protein coatings on nanostructured surfaces such as inorganic nanoparticles. The coatings can form naturally as part of the so-called protein corona or be purposely incorporated as functional elements to evade immune recognition or to enable enzymatic function, for example. To date, most relevant studies have examined the underlying adsorption processes on planar surfaces while the effect of nanoscale curvature on protein adsorption is still being unraveled across many dimensions. Herein, we investigated the ionic strength-dependent adsorption of antibacterial lysozyme protein onto planar and nanostructured silicon oxide surfaces by employing the quartz crystal microbalance-dissipation and localized surface plasmon resonance sensing techniques. Our findings revealed that lysozyme undergoes greater adsorption-related denaturation and spreading on planar surfaces which led to multilayer formation, while nanoscale curvature effects suppress protein denaturation on nanostructured surfaces leading to monolayer formation. We discuss these findings within the context of protein-surface and protein-protein interactions and how subtle changes in adsorption pathways can drive the formation of distinct macromolecular assemblies. Looking forward, we also discuss how such measurement strategies can enable mechanistic insights into the formation of protein coatings on nanostructured surfaces with broad implications for nano-bio interface science.

Impact of Polarity on Anisotropic Diffusion of Conjugated Organic Molecules on the (101̅0) Zinc Oxide Surface

We study the influence of polarity on the binding and diffusion of single conjugated organic molecules on the inorganic (1010) zinc oxide surface by means of all-atom molecular dynamics simulations at room temperature and above. In particular, we consider the effects of partial fluorination of the para-sexiphenyl (p-6P) molecule with chemical modifications of one head group (p-6P2F) or both (symmetric) head and tail (p-6P4F). Quantum-mechanical and classical simulations both result in consistent and highly distinct dipole moments and densities of the fluorinated molecules, which interestingly lead to a weaker adhesion to the surface than for p-6P. The diffusion for all molecules is found to be normal and Arrhenius-like for long times. Intriguingly, close to room temperature, the polar molecules diffuse 1–2 orders of magnitude slower compared to the p-6P reference in the apolar x-direction of the electrostatically heterogeneous surface, whereas in the polar y-direction, they diffuse 1–2 orders of magnitud...

Interfacial Behavior of Orthoborate Ionic Liquids at Inorganic Oxide Surfaces Probed by NMR, IR, and Raman Spectroscopy

Absorption modes and the reactivity of nonhalogenated ionic liquids (ILs) at inorganic oxide surfaces of γ-Al2O3, MgO, and SiO2 particles were characterized using multinuclear (11B, 31P, and 29Si) solid-state magic-angle-spinning NMR, FTIR, and Raman spectroscopy. ILs are composed of the trihexyl(tetradecyl)phosphonium cation, [P6,6,6,14]+, and bis(mandelato)borate, [BMB]−, or bis(salicylato)borate, [BScB]−, anions. Spectroscopic measurements were performed on room-temperature (298 K) samples and samples exposed to 15 h at 373 K. The single-pulse 11B NMR data of heated [P6,6,6,14][BMB] mixed with the inorganic oxides showed a significant change in the spectra of the anion for all three oxides. In contrast, no such spectral changes were detected for heated [P6,6,6,14][BScB] mixed with the inorganic oxides. 31P MAS NMR data for the IL/metal oxide systems revealed interactions between [P6,6,6,14]+ and the surfaces of oxides. A significant intensity of 31P CP-MAS NMR signals indicated a low mobility of cation...

Mechanism Analysis of Enhanced Li-Ion Conductivity in Mesoporous Silica-Based Solid Nano-Composite Electrolytes

Solid electrolytes with Li-ion conductivity higher than 1 mS/cm are required for the development of high capacity solid-state Li-ion batteries. In the past decade, several studies were done on the improvement of ion conductivity in composite materials by employing interface enhanced ion conduction at inorganic oxide surfaces such as silica, alumina or titania added to, for example, inorganic or polymer electrolytes. Also, composites of nanoparticles and mesoporous microparticles mixed with ionic-liquid electrolyte (ILE) have been proposed to promote the Li-ion conductivity along the particle or pore surface. However, so far the ionic conductivity was always lower than that of the original ILE due to the interrupted ionic paths by percolation from particle to particle. Monolithic nanoporous silica with ILE confined in the porous structures, also named “ionogels” have shown ion conductivities approaching the ILE bulk conductivity. These ionogels are fabricated by a sol-gel process e.g. by hydrolysis-condensation reaction with tetraethylorthosilicate (TEOS) precursor and typically formic acid where the ILE is added in the solution as the template for the silica to grow around. So far, the ionic conductivity of the confined ILE in the standard nanoporous oxide has never exceeded that of the ILE conductivity itself. By introduction of a surface functional group, an ion conductivity slightly higher than that of the bulk ILE was obtained, showing that surface interactions can be used to tailor the ion conductivity in these materials. In this paper, we show nanocomposite electrolyte (nano-SCE) materials with enhancements in ion conductivity exceeding 200% and ion conductivities up to 3mS/cm. The nano-SCE was fabricated in a similar way as the ionogels: a single-step sol-gel process with a TEOS precursor and with the ionic liquid electrolyte in the homogeneous precursor solution. The processing conditions were such that molecular ordering of the IL molecules was favored and the adsorbed interface layers provided free Li+ ions for enhanced Li-ion conductivity along the surface. Figure 1 shows the ion conductivity of the obtained solid pellet for a model system with (N-butyl- N-methyl pyrrolidinium bis(trifluoromethanesulfonyl) imide ([BMP]TFSI) and bis(trifluoromethanesulfonyl)imide lithium salt (LiTFSI). Importantly, the graph shows the difference between an ionogel material with a confined ILE and our nano-SCE. For the ionogels, the conductivity versus temperature behavior is the same as that for the bulk ILE, albeit with lower conductivity due to the fraction of inactive silica. Both the ionogel composites and the bulk ILE show the melting point of the ILE with a lower conductivity for the solid phase. For the nano-SCE, however, the melting point is no longer observed and the slope indicates that the formed nanocomposite material has a lower activation energy for diffusion than that of the bulk ILE and of the ionogels with the confined ILE. In this paper, we propose a mechanism for the observed behavior based on adsorption of the TFSI anion and subsequent molecular ordering and layering of the BMP cation and TFSI anions. The adsorbed layer has a solid-state like character and is therefore named as the mesophase layer. We will present experimental evidence for the interface interactions from FTIR spectra. Raman measurements confirm that the fraction of free Li+ ions increases in the composites. NMR measurements show that similar enhanced surface diffusion happens at nanoparticle systems but the interconnected pores in the SCE provide continuous pathways throughout the solid electrolyte nanostructure, ensuring the full effect of the surface enhancement is observed in contrast to analogous nanoparticle-ILE composites. To demonstrate the functionality of the nano-SCE as Li-ion electrolyte, cells with LFP cathodes were prepared. A technologically distinguishing feature of the nano-SCE, as for ionogels, is that it is applied as a liquid – via wet chemical coating – and only afterwards is converted into a solid. That way it is perfectly suited to be casted into dense powder electrodes where it fills all cavities and makes maximum contact, just as a liquid electrolyte does. A cell with 200Wh/L at 0.5C is demonstrated by casting of the nano-SCE precursor solution into the electrodes. The possibility of wet application of the nano-SCE precursor makes this technology also compatible with current Li-ion battery fabrication processes. Fig. 1 Temperature dependence of the ion conductivity for the ionic liquid electrolyte (ILE) with Li-TFSI and BMP-TFSI, for two silica ionogels with changing ILE content (x refers to the ratio of ILE to silica) and for our nano-SCE showing different behavior between the nano-SCE and the ILE it contains as a result of the mesophase layer formed on the silica pore surface. Figure 1

Adsorption-photometric and test-determination of copper in aqueous media using the oxides modifi ed with polyhexamethylene guanidine and bathocuproinedisulfonic acid

Adsorbents based on aluminium, zirconium and titanium oxides sequentially modified with polyhexamethylene guanidine ( PHMG ) and bathocuproinedisulfonic acid ( Batocuprsulfo ) were proposed for the adsorption-photometric and test-determination of copper in the variant of test tubes. An effective reagent fixation on the surface of inorganic oxides preliminarily modified with PHMG was attained in the range of pH 3-7. The adsorption capacity of the adsorbents for Batocuprsulfo was 22, 11, 7 mmol/g for Al 2 O 3 , ZrO 2 , and TiO 2 , respectively. Complex compound of Cu(I) with Batocuprsulfo and stoichiometry Cu:Batocuprsulfo=1:2 was formed on the adsorbents surface during Cu(II) adsorption in the presence of reducing agent – hydroxylamine; it was orange colored with maximum at 490 nm in the diffuse reflectance spectra. The quantitative extraction of Cu(I) and the maximum intensity of the surface color of Cu(I) complex was attained from the solutions with pH 6.0–7.0. This effect was used for developing the procedures for adsorption-photometric determination of Cu(I). The most sensitive procedure used aluminium oxide as an adsorbent matrix. The detection limit of Cu(I) determination calculated by the 3s-criterion was 0.02 μg/0.1 g of the adsorbent. The calibration curves were linear over the range of 0.1 - 15.0 μg/0.1 g. The test-procedure for determination of copper by the length of colored area was developed. The minimum determined concentration of copper was 2 mg/L. The proposed methods were used for the determination of Cu(I) in mineral and natural waters. The results obtained were confirmed by the added−found method, and the results of atomic-emission method with inductively coupled plasma. Key words : copper(II), adsorption, inorganic oxides, modified, bathocuproinedi sulfonic acid, diffuse reflectance spectroscopy, test determination (Russian) DOI: http://dx.doi.org/10.15826/analitika.2017.21.1.005 Didukh S.L., Losev V.N. Scientific research engineering centre “Kristall” Siberian Federal University, Svobodnyi pr., 79, Krasnoiarsk, 660041, Russian Federation

Revealing the role of catechol moieties in the interactions between peptides and inorganic surfaces.

Catechol (1,2-dihydroxy benzene) moieties are being widely used today in new adhesive technologies. Understanding their mechanism of action is therefore of high importance for developing their applications in materials science. This paper describes a single-molecule study of the interactions between catechol-related amino acid residues and a well-defined titanium dioxide (TiO2) surface. It is the first quantified measurement of the adhesion of these residues with a well-defined TiO2 surface. Single-molecule force spectroscopy measurements with AFM determined the role of different substitutions of the catechol moiety on the aromatic ring in the adhesion to the surface. These results shed light on the nature of interactions between these residues and inorganic metal oxide surfaces. This information is important for the design and fabrication of catechol-based materials such as hydrogels, coatings, and composites. Specifically, the interaction with TiO2 is important for the development of solar cells.

Patterned Grafted Lewis-Acid Sites on Surfaces: Olefin Epoxidation Catalysis Using Tetrameric Ti(IV)–Calix[4]arene Complexes

Tetrameric Ti(IV)–calix[4]arene complexes were synthesized and characterized as well as grafted on a hydroxylated SiO2 inorganic support as an example of patterned Lewis-acid sites on an inorganic oxide surface. These complexes consist of a novel calixarene organic ligand with varying lengths of tethers to a central aromatic core, and with the calixarene coordinating four titanium(IV)-cations via tetrahedral recognition on the lower rim. Catalysis of these materials was investigated with a probe reaction consisting of the epoxidation 1-octene with tert-butylhydroperoxide as the oxidant, and a comparison of their hydrolytic stability was performed. The oligomeric calix[4]arenes showed similar behavior in catalysis to the monomeric control, with the exception of the material with the shortest tether length, which shows a 1.3-fold higher activity that may be due to a modest cooperativity effect. In hydrolytic leaching tests, the oligomeric complexes showed higher stability compared to the monomeric complex, and this stability appeared to be more thermodynamic rather than kinetic in nature. We hypothesize that encapsulatation of the tetrameric active site within a silica mesopore of the support contributes to this stability.

Hydrolysis Catalysis of Miscanthus Xylan to Xylose Using Weak-Acid Surface Sites

Adsorption and hydrolysis of xylan polysaccharides extracted from Miscanthus biomass are demonstrated, using surface-functionalized MCN (mesoporous carbon nanoparticle) materials that comprise weak-acid sites, at a pH corresponding to biomass extract. Extracted xylan polysaccharides consist of a peak molecular weight of 2008 g/mol according to GPC (gel-permeation chromatography), corresponding to approximately 15 xylose repeat units, and, a calculated length of 7 nm and radius of gyration of 2.0 nm based on molecular dynamics simulations. A highly active material for the adsorption and depolymerization of xylan is a hydrothermally treated sulfonated MCN material, which consists of 90% weak-acid sites. In spite of the large polysaccharide size relative to its 1.6 nm pore radius, this material adsorbs up to 76% of xylan strands from extract solution, at a weight loading of 29% relative to MCN. Starting with a 9.7% xylose yield in Miscanthus extract, this material hydrolyzes extracted xylan to xylose, and achieves a 74.1% xylose yield, compared with 24.1% yield for the background reaction in acetate buffer, at 150 °C for 4 h. Catalytic comparisons with other MCN-based materials highlight the role of confinement and weak-acid surface sites, and provide some correlation between activity and phenolic OH acid-site density. However, the lack of a directly proportional correlation between weak-acid site density and catalyzed hydrolysis rate signifies that only a fraction of weak-acid surface sites are catalytically active, and this is likely to be the sites that are present in a high local concentration on the surface, which would be consistent with previously observed trends in the hydrolysis catalysis of chemisorbed glucans on inorganic-oxide surfaces.

P.155L: Late‐News Poster: Surface Monolayer Stabilized Vertically Aligned Liquid Crystals for Display Applications

AbstractThe surface monolayer stabilized vertically aligned liquid crystal (VA‐LC) mode is presented for television applications. Photo‐reactive self‐assembled monolayer (PR‐SAM) is formed on inorganic oxide surfaces. The SAM layer on oxide surfaces initially induce a homeotropic alignment of nematic LCs. Subsequent polymerization of the photo‐reactive SAM under applied electric field efficiently stabilizes LC alignment and induces a stable pretilt of LC molecules for four different directions in each pixel of the fishbone‐patterned VA‐cells. As results, improved electro‐optic characteristics, such as faster grey‐to‐grey response time, lower threshold voltage and enhanced brightness, are obtained after the polymerization‐induced stabilization of the photo‐reactive SAM.

Hydrophobization of Inorganic Oxide Surfaces Using Dimethylsilanediol

Dimethylsilanediol is a stable crystalline solid that was described in 1953. As the monomer of an important class of commercial products (poly(dimethylsiloxanes)-silicones, PDMS) and as a simple molecule in its own right (the silicon analog of acetone hydrate), it has been neglected by several fields of fundamental and applied research including the hydrophobization of inorganic oxide surfaces. We report that dimethylsilanediol is a useful reagent for the surface modification (hydrophobization) of oxidized silicon and other oxidized metal surfaces and compare the wetting properties of modified solids with those of conventionally modified surfaces. That water is the only byproduct of this modification reaction suggests that this and likely other silanediols are useful surface-modification agents, particularly when substrate corrosion or the competitive adsorption of byproducts is an issue. We note that dimethylsilanediol is volatile with a significant vapor pressure at room temperature. Vapor-phase surface modifications are also reported.

Conformally direct imprinted inorganic surface corrugation for light extraction enhancement of light emitting diodes

We describe the fabrication of corrugated inorganic oxide surface via direct single step conformal nanoimprinting to achieve enhanced light extraction in light emitting diodes (LEDs). Nanoscale zinc oxide (ZnO) and indium tin oxide (ITO) corrugated layer were created on a nonplanar GaN LED surface including metal electrode using ultraviolet (UV) assisted conformal nanoimprinting and subsequent inductively coupled plasma reactive ion etching (ICP-RIE) treatment. The total output powers of the surface corrugated LEDs increased by 45.6% for the patterned sapphire substrate LED and 41.9% for the flat c-plane substrate LED without any degradation of the electrical characteristics. The role of the nanoscale corrugations on the light extraction efficiency enhancement was examined using 3-dimensional finite-difference time-domain (FDTD) analysis. It was found that light scattering by subwavelength scale surface corrugation plays important role to redirect the trapped light into radiative modes. This straightforward inorganic oxide imprint method with inherent flexibility provides an efficient way to generate nanoscale surface textures for the production of high power LEDs and optoelectronic devices.

Organic-skinned inorganic nanoparticles: surface-confined polymerization of 6-(3-thienyl)hexanoic acid bound to nanocrystalline TiO2

There are many practical difficulties in direct adsorption of polymers onto nanocrystalline inorganic oxide surface such as Al2O3 and TiO2 mainly due to the insolubility of polymers in solvents or polymer agglomeration during adsorption process. As an alternative approach to the direct polymer adsorption, we propose surface-bound polymerization of pre-adsorbed monomers. 6-(3-Thienyl)hexanoic acid (THA) was used as a monomer for poly[3-(5-carboxypentyl)thiophene-2,5-diyl] (PTHA). PTHA-coated nanocrystalline TiO2/FTO glass electrodes were prepared by immersing THA-adsorbed electrodes in FeCl3 oxidant solution. Characterization by ultraviolet/visible/infrared spectroscopy and thermal analysis showed that the monolayer of regiorandom-structured PTHA was successfully formed from intermolecular bonding between neighbored THA surface-bound to TiO2. The anchoring functional groups (-COOH) of the surface-crawling PTHA were completely utilized for strong bonding to the surface of TiO2.

Rediscovering Silicones: “Unreactive” Silicones React with Inorganic Surfaces

Chemical reactions of linear trimethylsilyl-terminated poly(dimethylsiloxane)s with the surfaces of oxidized silicon, titanium, aluminum, and nickel are reported. These reactions lead to covalently attached poly(dimethylsiloxane) polymer chains and to hydrophobized inorganic surfaces. Linear silicones of this type (silicone oils) are generally not considered to be reactive with inorganic oxide surfaces, and an enormous research effort over the last 50 years to develop other silicon-containing reagents with reactive functional groups did not consider the simple alternative that we report. In retrospect, with the acknowledgment of the facile equilibration of siloxane chains with either acid or base catalysis (that was well-known in the 1940s and 1950s), the synthetic approach to functionalized inorganic surfaces by use of linear silicones is obvious. We also report the reactions of poly[3,3,3-trifluoropropyl)methylsiloxane], poly[(3-aminopropyl)methylsiloxane-co-dimethylsiloxane], poly(phenylmethylsiloxane-co-dimethylsiloxane), and poly(dimethylsiloxane-block-ethylene oxide) with oxidized silicon surfaces, which suggest that this reaction is general for silicones.

Origins of saccharide-dependent hydration at aluminate, silicate, and aluminosilicate surfaces

Sugar molecules adsorbed at hydrated inorganic oxide surfaces occur ubiquitously in nature and in technologically important materials and processes, including marine biomineralization, cement hydration, corrosion inhibition, bioadhesion, and bone resorption. Among these examples, surprisingly diverse hydration behaviors are observed for oxides in the presence of saccharides with closely related compositions and structures. Glucose, sucrose, and maltodextrin, for example, exhibit significant differences in their adsorption selectivities and alkaline reaction properties on hydrating aluminate, silicate, and aluminosilicate surfaces that are shown to be due to the molecular architectures of the saccharides. Solid-state (1)H, (13)C, (29)Si, and (27)Al nuclear magnetic resonance (NMR) spectroscopy measurements, including at very high magnetic fields (19 T), distinguish and quantify the different molecular species, their chemical transformations, and their site-specific adsorption on different aluminate and silicate moieties. Two-dimensional NMR results establish nonselective adsorption of glucose degradation products containing carboxylic acids on both hydrated silicates and aluminates. In contrast, sucrose adsorbs intact at hydrated silicate sites and selectively at anhydrous, but not hydrated, aluminate moieties. Quantitative surface force measurements establish that sucrose adsorbs strongly as multilayers on hydrated aluminosilicate surfaces. The molecular structures and physicochemical properties of the saccharides and their degradation species correlate well with their adsorption behaviors. The results explain the dramatically different effects that small amounts of different types of sugars have on the rates at which aluminate, silicate, and aluminosilicate species hydrate, with important implications for diverse materials and applications.

An IR study of the adsorption of ethylhydroxyethylcellulose on the surface of titanium and iron oxides under the action of mechanoactivation

The adsorption of hydrophilic ethylhydroxyethylcellulose (EHEC) polymer on the surface of TiO2 and Fe2O3 inorganic pigments under the action of intense mechanical actions was studied by infrared spectroscopy. Mechanoactivation methods included ultrasonic action and mechanical treatment at sonic frequencies. Intense action on TiO2 and Fe2O3 aqueous disperse systems activated the surface of inorganic oxides and intensified the adsorption of the polymer. It also caused the formation of adsorption-solvation EHEC layers with increased densities, which determined the sedimentation stability of disperse systems.

Asymmetric Hydrogen Bonding and Orientational Ordering of Water at Hydrophobic and Hydrophilic Surfaces: A Comparison of Water/Vapor, Water/Talc, and Water/Mica Interfaces

Interfaces involving aqueous fluid phases play critical roles in natural and technologically important systems, and the atomic scale differences between interfaces involving hydrophobic and hydrophilic substrates are essential to understanding and manipulating their chemical and physical properties. This paper compares computational molecular dynamics results for the atomic density profiles, H-bonding configurations, and orientational ordering of water molecules at three different and illustrative interfaces. These are the free liquid water surface, which can be considered hydrophobic, and the interfaces of liquid water with talc (001) and muscovite (001) surfaces, which are prototypical hydrophobic and hydrophilic inorganic oxide surfaces, respectively. The results clearly demonstrate the importance of substrate structure and composition in controlling interfacial behavior and illustrate the differences between the vapor interface and those involving solids. The atomic density profiles of water at the so...